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A baby girl was delivered by caesarean section at 39 weeks after unsuccessful attempts at vacuum extraction vaginal delivery. Her Apgar scores were 3 and 9 at one and five minutes, respectively. Resuscitation measures included bag mask manual ventilation for bradypnoea, bradycardia, cyanosis, and generalised hypotonia. She recovered promptly and was clinically stable.

The mother was a primigravida and the pregnancy was uneventful. The parents were non-consanguineous and declared no medical family history of note. Maternal serology tests were negative, as was Streptococcus group B screening. The antenatal ultrasound scans were normal.

Examination of the newborn showed persistent generalised hypotonia, the presence of an expressionless face, bitemporal flattening, tent shaped upper lips, a carp mouth with a high arched palate, an abnormal receding small jaw, and mild respiratory distress (fig 1⇓). Hyporeflexia was also present. Weight, length, and head circumference measures were appropriate for gestational age. At this point it was noticed that the mother had myopathic facial features, and after direct questioning the father confirmed the presence of “muscle disease” in his wife’s family. The newborn was admitted to the neonatal special care unit.

Fig 1 Newborn facies

Questions

1 What is the likely diagnosis?

2 What sign would you try to elicit to support the diagnosis?

3 What are the early management problems?

4 How would you confirm the diagnosis?

5 What is the prognosis for this infant?

Answers

1 What is the likely diagnosis?

Short answer

Myotonic dystrophy.

Long answer

Myotonic dystrophy type 1 is one of the most common hereditary neuromuscular diseases.12 The phenotypic expression of the disease and its clinical presentation are extremely heterogeneous, and symptoms may go unnoticed or not be taken seriously by carriers, as in the mother of this case. Obstetric problems are common, particularly the need for vacuum extraction (as in this case), …